Magnetic resonance imaging and spectroscopy is a non-invasive technique that allows probing human soft and hard tissue. In addition to being used as a diagnostic tool, magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) can be utilized in interventional procedures. While proton MRS and MRI has been employed extensively in brain cancer studies, substantially less research and development has succeeded in breast cancer research through magnetic resonance spectroscopy, in particular at high magnetic fields (e.g., at or above 3 T), albeit breast cancer is the most common malignancy and the number-one leading cause of cancer-related death in women. Each year, nearly 465,000 patients die from breast cancer worldwide, and 1,302,000 more women are newly diagnosed with this disease. Due to its relative good prognosis, nearly 4.4 million breast cancer survivors are living today; however, incidence rates of breast cancer are increasing in most countries. Mortality of breast cancer is mostly associated to metastasis. The current therapeutic interventions typically have limited effect to treat metastatic breast cancer and antiestrogen- chemo- and radiation-resistant tumors. Therefore, early detection is critical in breast cancer management.
A possible reason for having a lesser volume of breast cancer research and clinical success through MRS is that several disparate techniques are mature and used customarily at the clinic level, even though such techniques have substantive limitations. For instance, a technique readily employed is mammography, yet mammography screening(s) has false positive rate about 70%-80%. Ultrasonography is another technique that is often utilized in conjunction with mammography, however ultrasonography has lower specificity than mammography. Positron emission tomography/computed tomography (PET/CT) is another technique widely utilized and highly sensitive to detect breast cancer and metastasis for tumors larger than 1 cm; sensitivity decreases significantly for smaller tumors.
Regarding MRS and MRI techniques applied to breast cancer, proton MRS and MRI techniques can differentiate benign and malignant breast lesions in vivo. MRI has a high sensitivity (typically greater than 99%) in detecting breast cancer, but low specificity (37%-86%) with a high false-positive rate; MRS can improve breast cancer detection specificity. Currently, choline has been typically the only metabolite that has been observed reliably in human breast cancer by proton MRS, reaching a sensitivity and improved specificity of tumor detection of approximately 78% and 86%, respectively. To further specify, a family of proton MRSI (magnetic resonance spectroscopy imaging) methods based on a selective multiple quantum coherence transfer has been developed. Such technique can achieve complete lipid and water suppression in a single scan, which permits detection of low concentration metabolites, such as lactate, choline, and unsaturated lipid molecules as surrogate biomarkers of breast cancer. In an early patient study, a commercial body coil was used for radio frequency (RF) transmission at 2.1 T with an 8 cm surface coil employed for signal receiving. Experiments have also been conducted with various coil configurations for breast cancer MRI/MRS experiments in 3 T scanners.
Despite the foregoing developments associated with MRS and MRI experimentation, conventional equipment have not harnessed the benefits of high magnetic fields, which include dramatic increase in signal-to-noise ratio and spectral editing efficiency. Therefore, there is a need in the art to develop techniques and hardware that can operate reliably at high magnetic fields and lead to effective diagnosis.